BGE: Turn Physics off globally while keeping sensors
You need to keep the bullet physic engine to have many parts of the bge work, so don't disable that. Simply set all your objects to Static Physic Type. You will need to enable Actor and Ghost on them too.



The static physic type does not react to physics (no gravity, friction, etc). Actor lets the logic bricks "see" the object, and Ghost disables collisions.

With those three options on all your objects you should have a clean slate to build your own interactions off of.



To edit the physics properties on all your objects:

First set up one object like I describe above. Select all the objects, and keep the one you just edited the physics settings as the active object. Now press space and type "copy" choose "Copy Game Physics Properties to Selected". That's it, all the objects are set the same.